New Atari 5200 Controller Project

I am starting a crowd funded project for an new
Atari 5200 controller. It will be modular in design, do
all the functions of a real controller and have a
trackball function added as well.
In the design stages right now.. and have this campaign up
on indieGoGo.com
Please see the link
http://www.indiegogo.com/projects/advanced-modular-atari-5200-controller-project/x/674738
and if you have any suggestions on how it should operate, I would
like to hear them.. I have a small picture that shows it.. really
a basic design and will change..
Thanks.